Alcatel Mobile — Why they are not replacing the phone even it is in warranty period

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alcatel

I have given my phone at authorised service centre few days back, they said that phone has been sent to another centre for repaire.Still they have not responding my call.Sai communication center at secunderabad, they are not responding properly.If my phone is having a problem within warranty period, they have replace it.Why they are taking a lot of time to repaire and prolonging the time and returning same piece .pl look into this matter.Whom should i contact if they are not respond even for this complaint.